Nice Guidelines for Vte

Venous thromboembolism: reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in patients admitted to hospital

METHODS, EVIDENCE & GUIDANCE

Produced by the National Collaborating Centre for Acute Care

VENOUS THROMBOEMBOLISM PROPHYLAXIS

Published by the National Clinical Guideline Centre - Acute and Chronic Conditions (formerly the National Collaborating Centre for Acute Care) at The Royal College of Physicians, 11 St Andrews Place, Regents Park, London, NW1 4BT First published 2009 National Clinical Guideline Centre - Acute and Chronic Conditions 2009

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ForewordThe second report of session 2004-5 of The House of Commons Health Committee 'The Prevention of Venous Thromboembolism in Hospitalised Patients' opens with these worrying statistics: Each year 25,000 people in the UK die from venous thromboembolism. This figure includes both patients admitted for medical care of serious illnesses, as well as, those admitted for surgery. The report goes on to state that this is a larger number of deaths than are attributable to breast cancer, AIDS and road traffic accidents combined. It is 25 times the number of people who die as a result of MRSA infection 286. The sudden killer is pulmonary embolism (PE). That is a thrombus (or blood clot) which forms in the lower limb or pelvic veins and then comes loose and is carried in the blood to lodge in the lungs. Acute massive pulmonary embolism often kills immediately. If the patient survives the immediate haemodynamic consequences, death may still ensue in the days or weeks that follow. Survivors of the initial event may eventually recover after a protracted hospital course including some time in intensive care. Deep vein thrombosis (DVT) is in itself a cause of substantial morbidity and may lead to the development of post thrombotic syndrome (PTS) with chronic swelling and ulceration of the legs amongst its manifestations. Add this burden of morbidity to the estimated 25,000 deaths and it becomes a massive health problem. This is the perception of the situation as presented to the Health Committee, the CMO by expert advisors and patient representatives. Many of these deaths are in patients admitted for medical care but some have gone into hospital for a planned surgical operation such as joint replacement, gynaecological surgery or gall bladder removal intended to improve their quality of life, or for a cancer operation with the hope of cure. Characteristically it is several weeks after surgery, when recovery is in sight that this tragedy strikes. Our guideline covers all patients admitted to hospital and includes patients having surgery in day-case facilities. The magnitude of risk of venous thromboembolism (VTE) is dependent upon factors inherent in the operation and factors related to the individual patient. It is the combination of these factors which defines certain patients as at increased risk of VTE. A key part of this guidance is systematic risk assessment of all patients either on admission in the case of emergencies or prior to admission for planned surgery. This evaluation must be repeated regularly during a hospital stay because the balance of risks of bleeding and of VTE change as the condition of the patient changes. The part of our work relating to risk assessment has been done in close collaboration with the Department of Health and the Chief Medical Officer's VTE Working Group as part of the national VTE prevention strategy. Surgeons have been acutely aware of the dangers of VTE and have been central to research from the 1970s and 1980s642. Physical methods (such as graduated compression/anti-embolism stockings, foot impulse and intermittent pneumatic

FOREWARD

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compression devices) and pharmacological treatments (such as heparin and warfarin) have been studied in a plethora of randomised trials. Both physical and pharmacological treatments have been shown to reduce the incidence of DVT under study conditions. The difficulty is knowing how to implement prophylaxis in practice. Will reduction of DVTs translate into reduced death rates from PE? There is a question over whether the incidence of PE bears a reasonably consistent numerical relationship to the more frequent clinical event of DVT. We have not simply accepted this as an assumption but, where data sets allow both to be counted, we have tested the hypothesis. There appears to be a reasonably consistent association. However, this putative relationship between detectable lower limb DVT and fatal PE may break down in special cases such as knee replacement. The next question is whether reducing the incidence of DVT (the more numerous and more readily studied outcome) will result in a proportionate reduction in potentially fatal PE. Again we have tried to test this extrapolation against the data. We have conducted analyses where data are sufficient such as in studies of unfractionated heparin versus no prophylaxis: and found a similar reduction in fatal PEs473. A note of caution must remain however. We generally lack evidence for reduction in all-cause mortality which would require very large trials. The pharmacological methods introduce another consideration. They carry with them a new risk - that of bleeding. It is major bleeding events which are counted in the RCTs. We have to give guidance concerning the method of VTE prophylaxis which steers the safest course between the competing risks posed by thrombosis on the one hand and bleeding on the other. Major bleeding is clearly a threat to life but under some circumstances, a low volume bleed can be a very major complication. A few millilitres of bleeding into the brain, or compressing the spinal cord within the vertebral canal can cause death or permanent neurological damage. Small volumes of bleeding into a joint can cause the operation to fail and the patient will be worse off than before. It is a clinical problem which requires a meticulously researched and analysed evidence base. The potential health gains for the optimal strategy are great. An individual team will have patients who suffer PE and patients whose recovery is complicated by a treatment related bleed. The clinical difficulty is that both fatal pulmonary embolism and major bleeding have low event rates affecting fewer than one in a hundred patients. We cannot emphasise too strongly that it is evidence from the best available randomised controlled trials that we must use to quantify these competing risks. Clinical impressions cannot adequately capture the trade off between risk and benefit, particularly where both relate to infrequent clinical events or where the manefestations are delayed. It has been well shown that if clinicians base decisions for future patients on a recent adverse event in their own experience, those decisions are not likely to be in the best interest of future patients 108. The impossibility of basing a policy on clinical experience makes it essential to rely on evidence based guidance. It is appropriate that this guidance is made available for individual clinicians and their teams to use in framing locally implemented prophylactic policies. Hence VTE prophylaxis is an ideal subject for an evidence based guideline. The complex task has been undertaken in collaboration between the scientific staff at the NCC-AC, and the medical professionals of the Guideline Development Group (GDG). There are important changes expected in anticoagulation if the oral agents recently licensed or currently undergoing evaluation prove to be safe and consistently effective.

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We have been cautious in our recommendations, but if during the lifetime of this guideline they fulfill the hope that many doctors have for them, they will simplify practice that at present relies on daily injections of an anticoagulant, although there will need to be consideration of their drug interactions. A summary of our recommendations: Mechanical methods have been proven to be effective in surgical patients and do not to add the risk of bleeding. We have recommended these methods for patients at risk of bleeding and in combination with pharmacological methods for many groups of patients. However during our work on this guidance a large study in stroke patients did not show any beneficial effect of stockings in stroke patients but did show an increase in skin complications associated with their use. This influenced our recommendations 158. In patients at higher risk of VTE, the use of pharmacological methods is cost effective. In surgical patients these are often to be used in combination with mechanical prophylaxis such as stockings as this was the case in many of the RCTs on which we rely. There will be patients who are already on antiplatelet medication; there will also be some for whom aspirin may be recommended in the perioperative period for the reduction of risk of heart attack and stroke. This may present a therapeutic conflict: clinicians will be concerned about the risk of bleeding. It should be noted that while aspirin does reduce the risk of VTE to some extent, we have not recommended it as a form of VTE prophylaxis. Aspirin has an important role in cardiovascular perioperative risk reduction, but this is outside our scope. It might be tempting to see antiplatelet therapy as a convenient prophylactic two for one. To use this as a clinical justification for omitting recommended VTE pharmacological prophylaxis risks is not recommended because the protective effective of aspirin against VTE is insufficient Although there are many trials, we still found ourselves with uncertainties. For example, the true present day rate of DVT and PE is very hard to ascertain. Many more patients have less invasive surgery. Surgical patients get out of bed sooner. High emphasis is placed on early mobilisation and early discharge from hospital. Prophylaxis (both mechanical and pharmacological) is widely used, but practice varies and implementation is probably patchy. There is a strong sense that DVT and PE are less of a problem than they used to be in surgical patients but maybe it is hidden from the view of clinicians by early discharge rather than being truly reduced because 80% of DVT are subclinical and the average DVT occurs on the 7th postoperative day, long after the patient has left hospital. High quality monitoring of adverse events will be needed to ensure that these recommendations are as safe as they can be and we emphasise strongly the need to implement the research recommendations. These research recommendations specifically target the area where we found the biggest potential consequence from uncertainty. We also welcome the recommendation of the House of Commons Health Committee: Systems must be put in place to ensure that the NICE VTE guidelines are implemented 286. Once implemented, we need to monitor adverse events, both bleeding and venous thromboembolism to ensure that guidance is steering the safest course between those competing risks to all patients admitted to hospital. Professor Tom Treasure MD MS FRCS FRCP Chair, Guideline Development Group

CONTENTS

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ContentsFOREWORD ......................................................................................................................................................... 2 CONTENTS .......................................................................................................................................................... 5 GUIDELINE DEVELOPMENT GROUP MEMBERSHIP AND ACKNOWLEDGEMENTS................................................................... 11 GUIDELINE DEVELOPMENT GROUP..................................................................................................................... 11 ORTHOPAEDIC SUBGROUP ................................................................................................................................. 12 NCGC-ACC (FORMERLY NCC-AC) STAFF ON THE GUIDELINE DEVELOPMENT GROUP..................................... 13 ACKNOWLEDGEMENTS ...................................................................................................................................... 13 MEMBERS OF THE PREVIOUS SURGICAL GUIDELINE DEVELOPMENT GROUP ....................................................... 15 NCC-AC STAFF ON THE GUIDELINE DEVELOPMENT GROUP FROM PREVIOUS GUIDELINE ................................... 15 ACKNOWLEDGEMENTS FROM THE PREVIOUS GUIDELINE ................................................................................... 16 GUIDELINE REVIEW PANEL ................................................................................................................................ 17 STAKEHOLDER INVOLVEMENT........................................................................................................................... 18 ABBREVIATIONS ................................................................................................................................................ 19 GLOSSARY OF TERMS .......................................................................................................................................... 21 1 INTRODUCTION ........................................................................................................................................ 34 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 2 THE NEED FOR THIS GUIDELINE ........................................................................................................... 34 ASSUMPTIONS MADE IN THIS GUIDELINE ............................................................................................. 35 WHAT ARE CLINICAL PRACTICE GUIDELINES? ..................................................................................... 35 THE NATIONAL CLINICAL GUIDELINE CENTRE - ACUTE AND CHRONIC CONDITIONS ......................... 37 REMIT OF THE GUIDELINE.................................................................................................................... 37 WHAT THE GUIDELINE COVERS ........................................................................................................... 37 WHAT THE GUIDELINE DOES NOT COVER ............................................................................................. 37 WHO DEVELOPED THIS GUIDELINE? .................................................................................................... 38

SUMMARY OF RECOMMENDATIONS .............................................................................................................. 39 2.1 2.2 2.3 KEY PRIORITIES FOR IMPLEMENTATION............................................................................................... 39 THE COMPLETE LIST OF CLINICAL PRACTICE RECOMMENDATIONS ...................................................... 42 RECOMMENDATIONS FOR RESEARCH................................................................................................... 60

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METHODOLOGY........................................................................................................................................ 63 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 INCORPORATION AND UPDATE OF NICE CLINICAL GUIDELINE 46 ....................................................... 63 GUIDELINE METHODOLOGY ................................................................................................................. 64 DEVELOPING THE CLINICAL QUESTIONS .............................................................................................. 64 PATIENTS COVERED BY THIS GUIDELINE.............................................................................................. 66 OUTCOMES .......................................................................................................................................... 66 CLINICAL LITERATURE SEARCH ........................................................................................................... 69 HIERARCHY OF CLINICAL EVIDENCE ................................................................................................... 70 LITERATURE REVIEWING PROCESS ...................................................................................................... 71 METHODS FOR COMBINING DIRECT EVIDENCE..................................................................................... 71 METHODS FOR COMBINING DIRECT AND INDIRECT EVIDENCE ............................................................. 72 HEALTH ECONOMIC METHODS............................................................................................................. 76 DEVELOPMENT OF RECOMMENDATIONS .............................................................................................. 79 RESEARCH RECOMMENDATIONS.......................................................................................................... 80 PRIORITISATION OF RECOMMENDATIONS FOR IMPLEMENTATION ........................................................ 80 VALIDATION OF GUIDELINE ................................................................................................................. 80

63.16 3.17 4

VENOUS THROMBOEMBOLISM PROPHYLAXISRELATED NICE GUIDANCE .................................................................................................................. 80 UPDATING THE GUIDELINE .................................................................................................................. 81

DEVELOPMENT OF COST-EFFECTIVENESS MODEL ............................................................................................... 82 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 GENERAL APPROACH ........................................................................................................................... 82 RELATIVE RISKS .................................................................................................................................. 85 BASELINE RISKS .................................................................................................................................. 88 RESOURCE USE & COST ....................................................................................................................... 90 LIFE EXPECTANCY ............................................................................................................................... 97 QUALITY OF LIFE WEIGHTINGS ............................................................................................................ 98 POST-DISCHARGE / EXTENDED DURATION PROPHYLAXIS ..................................................................... 99 SENSITIVITY ANALYSES ..................................................................................................................... 101 FROM EVIDENCE TO RECOMMENDATIONS .......................................................................................... 106

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RISK, RISK REDUCTION AND HARM ..............................................................................................................107 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 INTRODUCTION .................................................................................................................................. 107 SOURCES OF INFORMATION ON RISKS, RISK REDUCTION AND HARM .................................................. 108 ABSOLUTE RISK OF VTE DURING SURGICAL ADMISSION ................................................................... 108 ABSOLUTE RISK OF VTE DURING MEDICAL ADMISSIONS ................................................................... 114 ABSOLUTE RISK OF MAJOR BLEEDING AFTER SURGERY ..................................................................... 115 ABSOLUTE RISK OF MAJOR BLEEDING AFTER MEDICAL ADMISSIONS ................................................. 117 INDIVIDUAL PATIENT RISK FACTORS AND RELATIVE RISKS OF VTE................................................... 117 INDIVIDUAL PATIENT RISK FACTORS AND RELATIVE RISK OF BLEEDING ............................................ 126 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 126 RECOMMENDATIONS FOR RESEARCH ................................................................................................. 134 SUMMARY OF RECOMMENDATIONS ................................................................................................... 135

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SUMMARY OF THE EFFECTIVENESS OF MECHANICAL AND PHARMACOLOGICAL PROPHYLAXIS ..................................138 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 INTRODUCTION .................................................................................................................................. 138 DESCRIPTION OF MECHANICAL AND PHARMACOLOGICAL PROPHYLAXIS ........................................... 139 SUMMARY OF EVIDENCE FOR MECHANICAL AND PHARMACOLOGICAL PROPHYLAXIS ........................ 142 SPECIFIC MECHANICAL COMPARISONS NOT PRESENTED ELSEWHERE ................................................. 147 SPECIFIC PHARMACOLOGICAL COMPARISONS NOT PRESENTED ELSEWHERE ...................................... 149 PATIENT VIEWS ................................................................................................................................. 150 RECOMMENDATIONS AND LINK TO EVIDENCE MECHANICAL PROPHYLAXIS .................................... 155 RECOMMENDATIONS AND LINK TO EVIDENCE PHARMACOLOGICAL PROPHYLAXIS ......................... 160 SUMMARY OF RECOMMENDATIONS ................................................................................................... 161

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NURSING CARE: EARLY MOBILISATION, PHYSIOTHERAPY AND HYDRATION ..........................................................163 7.1 7.2 7.3 7.4 7.5 EARLY MOBILISATION AND LEG EXERCISES ....................................................................................... 163 LEG ELEVATION................................................................................................................................. 164 HYDRATION....................................................................................................................................... 164 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 165 SUMMARY OF RECOMMENDATIONS ................................................................................................... 166

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VENA CAVAL FILTERS................................................................................................................................167 8.1 8.2 8.3 8.4 8.5 8.6 INTRODUCTION .................................................................................................................................. 167 CLINICAL EVIDENCE .......................................................................................................................... 167 ECONOMIC EVIDENCE ........................................................................................................................ 168 PATIENT VIEWS ................................................................................................................................. 168 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 168 SUMMARY OF RECOMMENDATIONS ................................................................................................... 169

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GASTROINTESTINAL, GYNAECOLOGICAL, LAPAROSCOPIC, THORACIC AND UROLOGICAL SURGERY ..........................170 9.1 9.2 9.3 9.4 9.5 9.6 INTRODUCTION .................................................................................................................................. 170 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 174 NETWORK META-ANALYSIS RESULTS ................................................................................................ 179 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 184 PATIENT VIEWS ................................................................................................................................. 189 SUMMARY OF EVIDENCE .................................................................................................................... 190

CONTENTS9.7 9.8 10

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RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 191 SUMMARY OF RECOMMENDATIONS ................................................................................................... 197

ELECTIVE HIP REPLACEMENT....................................................................................................................... 200 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 INTRODUCTION ................................................................................................................................. 200 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 200 NETWORK META-ANALYSIS RESULTS ................................................................................................ 206 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 212 PATIENT VIEWS ................................................................................................................................. 219 SUMMARY OF EVIDENCE ................................................................................................................... 220 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 221 SUMMARY OF RECOMMENDATIONS ................................................................................................... 224

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ELECTIVE KNEE REPLACEMENT .................................................................................................................... 226 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 INTRODUCTION ................................................................................................................................. 226 EVIDENCE OF METHODS OF THROMBOPROPHYLAXIS ......................................................................... 227 NETWORK META-ANALYSIS .............................................................................................................. 231 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 234 PATIENT VIEWS ................................................................................................................................. 239 SUMMARY OF EVIDENCE ................................................................................................................... 240 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 241 SUMMARY OF RECOMMENDATIONS ................................................................................................... 244

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HIP FRACTURE SURGERY ........................................................................................................................... 246 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 INTRODUCTION ................................................................................................................................. 246 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 246 NETWORK META-ANALYSIS RESULTS ................................................................................................ 251 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 255 PATIENT VIEWS ................................................................................................................................. 261 SUMMARY OF EVIDENCE ................................................................................................................... 261 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 262 RECOMMENDATIONS FOR RESEARCH................................................................................................. 267 SUMMARY OF RECOMMENDATIONS ................................................................................................... 267

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OTHER ORTHOPAEDIC SURGERY ................................................................................................................. 269 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 INTRODUCTION ................................................................................................................................. 269 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 269 NETWORK META-ANALYSIS RESULTS ................................................................................................ 271 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 272 PATIENTS VIEW ................................................................................................................................. 272 SUMMARY OF EVIDENCE ................................................................................................................... 272 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 273 RECOMMENDATIONS FOR RESEARCH................................................................................................. 276 SUMMARY OF RECOMMENDATIONS ................................................................................................... 276

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CRANIAL OR SPINAL SURGERY (NEUROLOGICAL SURGERY) ............................................................................ 278 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 INTRODUCTION ................................................................................................................................. 278 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 279 NETWORK META-ANALYSIS RESULTS ................................................................................................ 283 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 283 PATIENT VIEWS ................................................................................................................................. 283 SUMMARY OF EVIDENCE ................................................................................................................... 284 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 285 SUMMARY OF RECOMMENDATIONS ................................................................................................... 288

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CARDIAC SURGERY.................................................................................................................................. 290 15.1 15.2 15.3 15.4 INTRODUCTION ................................................................................................................................. 290 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 291 NETWORK META-ANALYSIS RESULTS ................................................................................................ 292 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 292

815.5 15.6 15.7 15.8 16

VENOUS THROMBOEMBOLISM PROPHYLAXISPATIENT VIEWS ................................................................................................................................. 293 SUMMARY OF EVIDENCE .................................................................................................................... 293 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 294 SUMMARY OF RECOMMENDATIONS ................................................................................................... 296

VASCULAR SURGERY ................................................................................................................................298 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 INTRODUCTION .................................................................................................................................. 298 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 299 NETWORK META-ANALYSIS RESULTS ................................................................................................ 300 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 301 PATIENT VIEWS ................................................................................................................................. 301 SUMMARY OF EVIDENCE .................................................................................................................... 301 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 302 SUMMARY OF RECOMMENDATIONS ................................................................................................... 305

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DAY-CASE SURGERY .................................................................................................................................307 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 INTRODUCTION .................................................................................................................................. 307 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 307 NETWORK META-ANALYSIS RESULTS ................................................................................................ 307 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 307 PATIENT VIEWS ................................................................................................................................. 307 SUMMARY OF EVIDENCE .................................................................................................................... 308 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 308 SUMMARY OF RECOMMENDATIONS ................................................................................................... 310

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OTHER SURGERY......................................................................................................................................312 18.1 18.2 18.3 18.4 18.5 18.6 18.7 18.8 INTRODUCTION .................................................................................................................................. 312 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 312 NETWORK META-ANALYSIS RESULTS ................................................................................................ 313 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 313 PATIENT VIEWS ................................................................................................................................. 313 SUMMARY OF EVIDENCE .................................................................................................................... 313 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 314 SUMMARY OF RECOMMENDATIONS ................................................................................................... 316

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ANAESTHESIA .........................................................................................................................................318 19.1 19.2 19.3 19.4 19.5 INTRODUCTION .................................................................................................................................. 318 CLINICAL EVIDENCE ON ANAESTHESIA .............................................................................................. 318 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 320 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 320 SUMMARY OF RECOMMENDATIONS ................................................................................................... 323

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SPINAL INJURY ........................................................................................................................................324 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 INTRODUCTION .................................................................................................................................. 324 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 324 NETWORK META-ANALYSIS RESULTS ................................................................................................ 327 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 327 PATIENT VIEWS ................................................................................................................................. 327 SUMMARY OF EVIDENCE .................................................................................................................... 327 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 329 RECOMMENDATIONS FOR RESEARCH ................................................................................................. 331 SUMMARY OF RECOMMENDATIONS ................................................................................................... 331

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LOWER LIMB PLASTER CASTS .......................................................................................................................333 21.1 21.2 21.3 21.4 21.5 21.6 INTRODUCTION .................................................................................................................................. 333 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 333 NETWORK META-ANALYSIS RESULTS ................................................................................................ 335 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 335 PATIENT VIEWS ................................................................................................................................. 335 SUMMARY OF EVIDENCE .................................................................................................................... 336

CONTENTS21.7 21.8 21.9 22

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RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 336 RECOMMENDATIONS FOR RESEARCH................................................................................................. 339 SUMMARY OF RECOMMENDATIONS ................................................................................................... 339

MAJOR TRAUMA .................................................................................................................................... 341 22.1 22.2 22.3 22.4 22.5 22.6 22.7 22.8 INTRODUCTION ................................................................................................................................. 341 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 341 NETWORK META-ANALYSIS RESULTS ................................................................................................ 344 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 344 PATIENT VIEWS ................................................................................................................................. 344 SUMMARY OF EVIDENCE ................................................................................................................... 345 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 346 SUMMARY OF RECOMMENDATIONS ................................................................................................... 349

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GENERAL MEDICAL PATIENTS ..................................................................................................................... 352 23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8 23.9 INTRODUCTION ................................................................................................................................. 352 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 352 NETWORK META-ANALYSIS RESULTS ................................................................................................ 355 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 360 PATIENT VIEWS ................................................................................................................................. 363 SUMMARY OF EVIDENCE ................................................................................................................... 363 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 364 RECOMMENDATIONS FOR RESEARCH................................................................................................. 368 SUMMARY OF RECOMMENDATIONS ................................................................................................... 369

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STROKE PATIENTS ................................................................................................................................... 371 24.1 24.2 24.3 24.4 24.5 24.6 24.7 24.8 24.9 INTRODUCTION ................................................................................................................................. 371 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 371 NETWORK META-ANALYSIS RESULTS ................................................................................................ 375 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 375 PATIENT VIEWS ................................................................................................................................. 375 SUMMARY OF EVIDENCE ................................................................................................................... 375 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 376 RECOMMENDATIONS FOR RESEARCH................................................................................................. 380 SUMMARY OF RECOMMENDATIONS ................................................................................................... 381

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ACUTE CORONARY SYNDROMES ................................................................................................................ 382 25.1 25.2 25.3 25.4 25.5 25.6 25.7 25.8 INTRODUCTION ................................................................................................................................. 382 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 382 NETWORK META-ANALYSIS RESULTS ................................................................................................ 384 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 385 PATIENT VIEWS ................................................................................................................................. 385 SUMMARY OF EVIDENCE ................................................................................................................... 385 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 385 SUMMARY OF RECOMMENDATIONS ................................................................................................... 389

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CANCER ................................................................................................................................................ 391 26.1 26.2 26.3 26.4 26.5 26.6 26.7 26.8 26.9 INTRODUCTION ................................................................................................................................. 391 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 391 NETWORK META-ANALYSIS RESULTS ................................................................................................ 393 COST-EFFECTIVENESS EVIDENCE....................................................................................................... 393 PATIENT VIEWS ................................................................................................................................. 393 SUMMARY OF EVIDENCE ................................................................................................................... 394 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 394 RECOMMENDATIONS FOR RESEARCH................................................................................................. 397 SUMMARY OF RECOMMENDATIONS ................................................................................................... 398

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PATIENTS WITH CENTRAL VENOUS CATHETERS ............................................................................................... 400 27.1 27.2 INTRODUCTION ................................................................................................................................. 400 EVIDENCE OF METHODS OF VTE PROPHYLAXIS ................................................................................ 401

1027.3 27.4 27.5 27.6 27.7 27.8 27.9 28

VENOUS THROMBOEMBOLISM PROPHYLAXISNETWORK META-ANALYSIS RESULTS ................................................................................................ 405 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 405 PATIENT VIEWS ................................................................................................................................. 405 SUMMARY OF EVIDENCE .................................................................................................................... 405 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 406 RECOMMENDATIONS FOR RESEARCH ................................................................................................. 408 SUMMARY OF RECOMMENDATIONS ................................................................................................... 408

PALLIATIVE CARE .....................................................................................................................................410 28.1 28.2 28.3 28.4 28.5 28.6 28.7 28.8 28.9 INTRODUCTION .................................................................................................................................. 410 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 410 NETWORK META-ANALYSIS RESULTS ................................................................................................ 410 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 410 PATIENT VIEWS ................................................................................................................................. 411 SUMMARY OF EVIDENCE .................................................................................................................... 411 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 411 RECOMMENDATIONS FOR RESEARCH ................................................................................................. 413 SUMMARY OF RECOMMENDATIONS ................................................................................................... 413

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CRITICAL CARE ........................................................................................................................................414 29.1 29.2 29.3 29.4 29.5 29.6 29.7 29.8 INTRODUCTION .................................................................................................................................. 414 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 415 NETWORK META-ANALYSIS RESULTS ................................................................................................ 416 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 416 PATIENT VIEWS ................................................................................................................................. 416 SUMMARY OF EVIDENCE .................................................................................................................... 417 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 417 SUMMARY OF RECOMMENDATIONS ................................................................................................... 419

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PREGNANCY AND UP TO 6 WEEKS POST PARTUM ...........................................................................................421 30.1 30.2 30.3 30.4 30.5 30.6 30.7 30.8 30.9 INTRODUCTION .................................................................................................................................. 421 EVIDENCE FOR RISK FACTORS FOR PREGNANCY AND POSTPARTUM ................................................... 422 EVIDENCE OF METHODS OF PROPHYLAXIS ......................................................................................... 424 NETWORK META-ANALYSIS RESULTS ................................................................................................ 425 COST-EFFECTIVENESS EVIDENCE ....................................................................................................... 425 PATIENT VIEWS ................................................................................................................................. 425 SUMMARY OF EVIDENCE .................................................................................................................... 425 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 426 SUMMARY OF RECOMMENDATIONS ................................................................................................... 431

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PATIENTS REQUIRING ANTIPLATELET AGENTS AND ANTICOAGULANTS FOR OTHER REASONS ...................................433 31.1 31.2 31.3 31.4 31.5 31.6 ANTIPLATELET AGENTS ..................................................................................................................... 433 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 434 ANTICOAGULANT AGENTS ................................................................................................................. 437 RECOMMENDATIONS AND LINK TO EVIDENCE ................................................................................... 437 RECOMMENDATIONS FOR RESEARCH ................................................................................................. 439 SUMMARY OF RECOMMENDATIONS ................................................................................................... 439

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PROVISION OF INFORMATION TO PATIENTS AND PLANNING FOR DISCHARGE ......................................................442 32.1 32.2 32.3 32.4 32.5 32.6 32.7 32.8 INTRODUCTION .................................................................................................................................. 442 SUMMARY OF IDENTIFIED STUDIES .................................................................................................... 443 CONCLUSIONS ON INFORMATION FOR PATIENTS ................................................................................ 444 SUMMARY OF EVIDENCE .................................................................................................................... 444 RECOMMENDATIONS AND LINK TO EVIDENCE IN HOSPITAL PATIENT INFORMATION ....................... 445 RECOMMENDATIONS AND LINK TO EVIDENCE PLANNING FOR DISCHARGE ...................................... 448 RELATED RECOMMENDATIONS .......................................................................................................... 450 SUMMARY OF RECOMMENDATIONS ON PROVISION OF INFORMATION FOR PATIENTS ......................... 450

BIBLIOGRAPHY .................................................................................................................................................452

GUIDELINE DEVELOPMENT GROUP MEMBERSHIP AND ACKNOWLEDGEMENTS

11

Guideline development group membership and acknowledgementsGuideline development groupProfessor Tom Treasure (Chair) Honorary Professor and Honorary Consultant, Clinical Operational Research Unit, University College London DVT Nurse Specialist, Portsmouth Specialist NHS Trust, Queen Alexandria Hospital, Portsmouth Consultant in General Medicine and Critical Care, Sellyoak Hospital, Birmingham Professor of Genetic Epidemiology, British Heart Foundation Senior Research Fellow, and Honorary Consultant Physician University College London Hospitals NHS Foundation Trust Consultant Respiratory Physician, Northern General Hospital, Sheffield Consultant in Departments of Haematology, Pathology and Rheumatology, Guys and St. Thomass Foundation Trust, London Consultant Physician and Clinical Pharmacologist, City Hospital, Birmingham Consultant Orthopaedic Surgeon, University Hosptial North Staffordshire (From June 2008) Patient representative, Bury Clinical Senior Lecturer and Honorary Consultant in Palliative Medicine, Royal Gwent Hospital, Newport

Mrs Kim Carter

Dr Nandan Gautam Professor Aroon Hingorani

Dr Rodney Hughes Professor Beverley Hunt

Dr Nigel Langford Mr Donald McBride

Mr Paul Mainwaring Dr Simon Noble

12

VENOUS THROMBOEMBOLISM PROPHYLAXIS Professor of Vascular Surgery, Freeman Hospital, Newcastle upon Tyne Nurse Director, 3 Counties Cancer Network, Gloucestershire, Herefordshire and South Worcestershire Patient representative, Cheshire (From Febuary 2008) Patient Representative, Renfrewshire (From September 2007 until January2008)

Professor Gerard Stansby Ms Annie Young

Dr Peter Walton Gordon McPherson

Orthopaedic subgroupProfessor Tom Treasure (Chair) Honorary Professor and Honorary Consultant, Clinical Operational Research Unit, University College London Consultant Orthopaedic Oncologist, Royal Orthopaedic Hospital, Birmingham Consultant Orthopaedic Surgeon, Royal Bournemouth Hospital Professor of Orthopaedics, Royal Liverpool University Hospital Consultant Orthopaedic Surgeon, The James Cook University Hospital, Middlesbrough Consultant Orthopaedic Surgeon, University Hospital North Staffordshire Consultant Orthopaedic Surgeon, Southampton University Hospital Patient Representative, Derbyshire Consultant Orthopaedic Surgeon, Cumberland Infirmary, Carlisle DVT Nurse Specialist, Portsmouth Specialist NHS Trust, Queen Alexandria Hospital, Portsmouth

Mr. Simon Carter Mr. Nick Fiddian

Prof. Simon Frostick Prof. Paul Gregg Mr. Donald McBride Mr. David Warwick Mr. Nick Welch Ms. Claire Young Mrs Kim Carter


13

NCGC-ACC (formerly NCC-AC) staff on the guideline development groupMrs Karen Head Dr Anayo Akunne Mrs Nina Balachander Dr John Browne Dr Lee-Yee Chong Dr Jennifer Hill Ms Kate Homer Ms Hanna Lewin Mr. Carlos Sharpin Ms Nicola Sloan Mr David Wonderling Research Fellow / Project Manager (until August 2009) Health Economist (from June 2008) Research Fellow / Project Manager (from July 2009) Methodological Advisor (until August 2008) Research Associate (from March 2008) Director of the NCC-AC Research Associate (September 2007 January 2008) Information Specialist (Until January 2009) Information Specialist / Research Associate Research Associate (Until January 2008) Senior Health Economist

AcknowledgementsThe development of this guideline was greatly assisted by the following people: > NCGC-ACC (formerly NCC-AC) Saoussen Ftouh, Abigail Jones, Clare Jones, Caroline Lawson, Kamsha Maharaj, Fulvia Ronchi > Non-NCGC-ACC Reviewers Dr Tom Cahill Expert Advisors (Profession Section where advice was provided) Nicola Cooper (Statistician network meta-analysis), David Fitzmaurice (GP post discharge prophylaxis), David Goldhill (Anaesthetist Anaesthetia ), Ian Greer (Dean of medical school pregnancy and post partum), Nihal Gurusinghe (Neurosurgeon Neurosurgery and spinal injury),

14

VENOUS THROMBOEMBOLISM PROPHYLAXIS Mike Laffan (Haematologist- pregnancy and post partum) Peter McCallum (Haematologist pregnancy and post partum) Lucy Mackillop (Obstetric physician pregnancy and post partum) Catherine Nelson-Piercy (Obstetric physician pregnancy and post partum) Alex Sutton (Statistician network meta-analysis), Douglas Wardlaw (Spinal Surgeon neurosurgery and other orthopaedic surgery)


15

Members of the previous surgical guideline development groupProfessor Tom Treasure (Chair) Consultant Thoracic Surgeon, Guys Hospital, London Mr Nigel Acheson Dr Ricky Autar Consultant Gynaecological Oncologist, Royal Devon & Exeter Hospital Clinical Nurse Consultant, University Hospitals of Leicester NHS trust & Principal Lecturer in Nursing, De Montfort University Clinical Epidemiologist, Clinical Trial Service Unit (CTSU), Oxford DVT Nurse Specialist, Portsmouth Hospitals NHS Trust, Queen Alexandra Hospital, Portsmouth Consultant Orthopaedic Oncologist, Royal Orthopaedic Hospital, Birmingham Patient Representative Consultant Anaesthetist, The Royal National Orthopaedic Hospital, Stanmore Consultant Haematologist, North Middlesex University Hospital Director of Clinical Pharmacy, University College Hospital, London Patient Representative

Professor Colin Baigent Mrs Kim Carter Mr Simon Carter Mr David Farrell Dr David Goldhill Dr John Luckit Mr Robin Offord Mr Adam Thomas

NCC-AC staff on the guideline development group from previous guidelineDr Jennifer Hill Dr Philippa Davies Dr Saoussen Ftouh Mr Enrico De Nigris Mr Peter B Katz Mr Carlos Sharpin Mr David Wonderling Dr Arash Rashidian Director of NCC-AC / Project Manager Research Associate / Project Manager Project Manager (from October 2006) Health Economist Information Scientist Information Scientist / Research Associate Senior Health Economist Methodological Advisor

16


Acknowledgements from the previous guidelineThe development of the NICE Surgical guideline was greatly assisted by the following people: NCC-AC Funsho Akinluyi, Rifna Aktar, Gianluca Baio, Sophie Capo-Bianco, Kelly Dickinson, Susan Murray, Kathryn Oliver, Veena Mazarello Paes, Jacqueline Rainsbury, Nishanthi Talawila, Louise Thomas, Jennifer Wood. Expert Advisors John Black, Jonathan Emberson, Mark Emberton, Nihal Gurusinghe, Tim Lees, Frank Smith, Sir Peter Morris, David Whillier.


17

Guideline review panelThe Guideline Review Panel is an independent panel that overseas the development of the guideline and takes responsibility for monitoring its quality. The members of the Guideline Review Panel will be added when available.

18


Stakeholder involvementAnticoagulation Europe ArjoHuntleigh Barts and the London NHS Trust Bayer HealthCare Boehringer Ingelheim Ltd Bristol-Myers Squibb Pharmaceuticals Limited British Association of Day Surgery British Association of Knee Surgery British Association of Spine Surgeons (BASS) British Association Of Stroke Physicians (BASP) British Cardiovascular Society British Elbow and Shoulder Society (BESS) British Hip Society British Orthopaedic Association British Society for Haematology British Society for Surgery of the Hand Chelsea/Westminster hospital Christie Hospital NHS Foundation Trust Colchester Hospital University NHS Foundation Trust Cornwall Isles of Scilly Community Health Services Covidien (UK) Commericial Ltd (Formerly: Tyco Healthcare (UK) Commericial Ltd) Department of Health GlaxoSmithKline Griffiths & Nielsen Ltd Harrogate and District NHS Foundation Trust Intavent Orthofix Kings College Hospital NHS Foundation Trust Luton & Dunstable Hospital NHS Foundation Mid Essex Hospitals Trust Milton Keynes Hospital Foundation Trust North Middlesex University Hospital Paediatric Intensive Care Society Pfizer Limited Plymouth teaching Primary Care Trust Poole Hospital NHS Foundation Trust Queen Elizabeth Hospital Royal Brompton & Harefield NHS Trust Royal College of Midwives Royal College of Nursing Royal College of Obstetricians & Gynaecologists Royal College of Pathologists Salisbury NHS Foundation Trust Sanofi Aventis SBNS (Society of British Neurological Surgeons) Sedgefield PCT (Now County Durham PCT) Sheffield Teaching Hospital NHS Foundation Trust Sherwood Forest Hospitals NHS Foundation Trust Society of Vascular Nurses St. Helens & Knowsley Teaching Hospitals NHS Trust The Society and College of Radiographers Trafford Healthcare NHS Trust UK Thromboprophylaxis Forum University Hospital Birmingham University Hospital of North Staffordshire NHS Trust University of Hertfordshire Vascular Society of Great Britain and Ireland Whittington Hospital Wirral University Teaching Hospital NHS Trust

SUMMARY OF RECOMMENDATIONS

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AbbreviationsACS AES BMI BNF CCA CCT CEA CI CPM CRT CTEPH CUA CVC DH DVT FID FP GCS GDG GP GPRD GRADE GRP HD HES HIT HRQL HTA ICER ICU IPCD INB INR IPCD IV LD LMWH Acute Coronary Syndrome Anti-embolism stockings Body mass index British National Formulary Cost-consequences analysis Controlled clinical trial Cost-effectiveness analysis Confidence interval Continuous passive motion Catheter related thrombosis Chronic thromboembolic pulmonary hypertension Cost-utility analysis Central venous catheters Department of Health Deep-vein thrombosis Foot impulse devices Forest Plot Graduated compression stocking Guideline Development Group General Practitioner General Practice Research Database Guidelines Recommendations Assessment Development Evaluation Guideline Review Panel High dose Hospital Episode Statistics Heparin-induced thrombocytopenia Health-related quality of life Health technology assessment Incremental cost-effectiveness ratio Intensive Care Unit Intermittent pneumatic compression devices Incremental net benefit International normalized ratio Intermittent pneumatic compression devices Intravenous Low dose Low molecular weight heparin

20 LOS LY MB MHRA NCC-AC NCGC NHS NICE NMA NNT OAC OR PASA PE PHT PICO PPIP PSA PTS QALY RCT RR sc SR UKOSS UFH VKA vs VTE

VENOUS THROMBOEMBOLISM PROPHYLAXIS Length of stay Life-year Major Bleeding Medicines and Healthcare Products Regulatory Agency National Collaborating Centre for Acute Care National Clinical Guideline Centre for Acute and Chronic Conditions (Formerly known as the National Collaborating Centre for Acute Care) National Health Service National Institute for Health and Clinical Excellence Network meta-analysis Number needed to treat Oral anticoagulants Odds ratio NHS Purchasing and Supply Agency Pulmonary embolism Chronic thromboembolic pulmonary hypertension Framework incorporating patients, interventions, comparisons, outcomes Patient and Public Involvement Programme Probabilistic sensitivity analysis Post-thrombotic syndrome Quality-adjusted life year Randomised controlled trial Relative risk Subcutaneous Systematic review United Kingdom Obstetric Surveillance System Unfractionated heparin Vitamin K antagonist Versus Venous thromboembolism

GLOSSARY OF TERMS

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Glossary of termsAbsolute effect Absolute risk reduction (Risk difference) Abstract Acute medical admission The difference in the risk of an event between two groups (one subtracted from the other) in a comparative study. See absolute effect

Summary of a study, which may be published alone or as an introduction to a full scientific paper. A medical admission concerned with the immediate and early specialist management of adult patients suffering from a wide range of medical conditions who present to, or from within, hospitals, requiring urgent or emergency care The extent to which the patients behaviour matches the prescribers recommendations. Adherence emphasises the need for agreement and that the patient is free to decide whether or not to adhere to the doctors recommendation. 472 A statistical procedure in which the effects of differences in composition of the populations being compared (or treatment given at the same time) have been minimised by statistical methods. A flow chart of the clinical decision pathway described in the guideline, where decision points are represented with boxes, linked with arrows. The process used to prevent advance knowledge of group assignment in a RCT. The allocation process should be impervious to any influence by the individual making the allocation, by being administered by someone who is not responsible for recruiting participants. Any agent used to prevent the formation of blood clots. These include oral agents, such as warfarin, and others which are injected into a vein or under the skin, such as heparin. Hosiery which, when worn on the leg, exerts graduated compression on the leg surface and is intended to reduce the incidence of deep vein thrombosis. These should not be confused with graduated compression stockings which have a different pressure profile and are not used for the prevention of venous thromboembolism. The degree to which the results of an observation, study or review

Adherence

Adjustment

Algorithm (in guidelines) Allocation concealment

Anticoagulants

Anti-embolism stockings

Applicability

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VENOUS THROMBOEMBOLISM PROPHYLAXIS are likely to hold true in a particular clinical practice setting.

Appraisal of Guidelines, Research and Evaluation (AGREE) Arm (of a clinical study) Association Audit Baseline

An international collaboration of researchers and policy makers whose aim is to improve the quality and effectiveness of clinical practice guidelines (http://www.agreecollaboration.org). The AGREE instrument, developed by the group, is designed to assess the quality of clinical guidelines. Sub-section of individuals within a study who receive one particular intervention, for example placebo arm. Statistical relationship between two or more events, characteristics or other variables. The relationship may or may not be causal. See Clinical audit. The initial set of measurements at the beginning of a study (after run-in period where applicable), with which subsequent results are compared. Systematic (as opposed to random) deviation of the results of a study from the true results that is caused by the way the study is designed or conducted. Keeping the study participants, caregivers, researchers and outcome assessors unaware about the interventions to which the participants have been allocated in a study. Costs of purchasing major capital assets (usually land, buildings or equipment). Capital costs represent investments at one point in time. Someone other than a health professional who is involved in caring for a person with a medical condition. Comparative observational study in which the investigator selects individuals who have experienced an event (For example, developed a disease) and others who have not (controls), and then collects data to determine previous exposure to a possible cause. Report of a number of cases of a given disease, usually covering the course of the disease and the response to treatment. There is no comparison (control) group of patients. Abnormally elevated blood pressure within the pulmonary circuit (pulmonary artery).

Bias

Blinding (masking)

Capital costs Carer (caregiver) Case-control study

Case series

Chronic thrombembolic pulmonary hypertension Clinical audit

A quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change. The extent to which an intervention is active when studied under controlled research conditions. The extent to which an intervention produces an overall health benefit in routine clinical practice. The effect that a guideline recommendation is likely to have on the

Clinical efficacy Clinical effectiveness Clinical impact

GLOSSARY OF TERMS treatment or treatment outcomes, of the target population. Clinical question

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In guideline development, this term refers to the questions about treatment and care that are formulated to guide the development of evidence-based recommendations. A healthcare professional providing direct patient care, for example doctor, nurse or physiotherapist. A closely grouped series of events or cases of a disease or other related health phenomena with well-defined distribution patterns, in relation to time or place or both. Alternatively, a grouped unit for randomisation. A regularly updated electronic collection of evidence-based medicine databases, including the Cochrane Database of Systematic Reviews. A systematic review of the evidence from randomised controlled trials relating to a particular health problem or healthcare intervention, produced by the Cochrane Collaboration. Available electronically as part of the Cochrane Library. A retrospective or prospective follow-up study. Groups of individuals to be followed up are defined on the basis of presence or absence of exposure to a suspected risk factor or intervention. A cohort study can be comparative, in which case two or more groups are selected on the basis of differences in their exposure to the agent of interest. Co-existence of more than one disease or an additional disease (other than that being studied or treated) in an individual. Similarity of the groups in characteristics likely to affect the study results (such as health status or age). The extent to which a person adheres to the health advice agreed with healthcare professionals. May also be referred to as adherence or concordance. This is a recent term whose meaning has changed. It was initially applied to the consultation process in which prescriber and patient agree therapeutic decisions that incorporate their respective views, but now includes patient support in medicine-taking as well as prescribing communication. Concordance reflects social values but does not address medicine-taking and may not lead to improved adherence472 Compilation of papers presented at a conference. A range of values for an unknown population parameter with a stated confidence (conventionally 95%) that it contains the true value. The interval is calculated from sample data, and generally straddles the sample estimate. The confidence value means that if the method used to calculate the interval is repeated many times, then that proportion of intervals will actually contain the true value. In a study, confounding occurs when the effect of an intervention on

Clinician Cluster

Cochrane Library

Cochrane Review

Cohort study

Comorbidity Comparability Compliance

Concordance

Conference proceedings Confidence interval (CI)

Confounding

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VENOUS THROMBOEMBOLISM PROPHYLAXIS an outcome is distorted as a result of an association between the population or intervention or outcome and another factor (the confounding variable) that can influence the outcome independently of the intervention under study.

Consensus methods

Techniques that aim to reach an agreement on a particular issue. Formal consensus methods include Delphi and nominal group techniques, and consensus development conferences. In the development of clinical guidelines, consensus methods may be used where there is a lack of strong research evidence on a particular topic. Expert consensus methods will aim to reach agreement between experts in a particular field. A group of patients recruited into a study that receives no treatment, a treatment of known effect, or a placebo (dummy treatment) in order to provide a comparison for a group receiving an experimental treatment, such as a new drug. A study testing a specific drug or other treatment involving two (or more) groups of patients with the same disease. One (the experimental group) receives the treatment that is being tested, and the other (the comparison or control group) receives an alternative treatment, a placebo (dummy treatment) or no treatment. The two groups are followed up to compare differences in outcomes to see how effective the experimental treatment was. A CCT where patients are randomly allocated to treatment and comparison groups is called a randomised controlled trial. A type of economic evaluation where both costs and benefits of healthcare treatment are measured in the same monetary units. If benefits exceed costs, the evaluation would recommend providing the treatment. A type of economic evaluation where various health outcomes are reported in addition to cost for each intervention, but there is no overall measure of health gain. An economic study design in which consequences of different interventions are measured using a single outcome, usually in natural units (For example, life-years gained, deaths avoided, heart attacks avoided, cases detected). Alternative interventions are then compared in terms of cost per unit of effectiveness. An explicit mathematical framework, which is used to represent clinical decision problems and incorporate evidence from a variety of sources in order to estimate the costs and health outcomes. A form of cost-effectiveness analysis in which the units of effectiveness are quality-adjusted life-years (QALYs). Where a joint is moved continuously, either by another person bending it or by a machine. The Bayesian equivalent of a confidence interval. A systematic way of reaching decisions, based on evidence from research. This evidence is translated into probabilities, and then into

Control group

Controlled clinical trial (CCT)

Cost benefit analysis

Cost-consequences analysis (CCA) Cost-effectiveness analysis (CEA)

Cost-effectiveness model Cost-utility analysis (CUA) Continuous passive motion Credible interval Decision analysis

GLOSSARY OF TERMS diagrams or decision trees which direct the clinician through a succession of possible scenarios, actions and outcomes. Decision analytic techniques

25

A way of reaching decisions, based on evidence from research. This evidence is translated into probabilities, and then into diagrams or decision trees that direct the clinician through a succession of possible scenarios, actions and outcomes. A clear specification of the interventions, patient populations and outcome measures and perspective adopted in an evaluation, with an explicit justification, relating these to the decision which the analysis is to inform. Venous thrombosis that occurs in the deep veins in the legs, thighs, or pelvis. Costs and perhaps benefits incurred today have a higher value than costs and benefits occurring in the future. Discounting health benefits reflects individual preference for benefits to be experienced in the present rather than the future. Discounting costs reflects individual preference for costs to be experienced in the future rather than the present. Refers to a part of the body that is farther away from the centre of the body than another part. An intervention is said to be dominated if there is an alternative intervention that is both less costly and more effective. The prescribed amount of a drug to be taken, including the size and timing of the doses. A study in which neither the subject (patient) nor the observer (investigator/clinician) is aware of which treatment nor intervention the subject is receiving. The purpose of blinding is to protect against bias. See Deep-vein thrombosis. A participant who withdraws from a clinical trial before the end. Comparative analysis of alternative health strategies (interventions or programmes) in terms of both their costs and consequences. The observed association between interventions and outcomes or a statistic to summarise the strength of the observed association.

Decision problem

Deep-vein thrombosis (DVT) Discounting

Distal Dominance Dosage Double blind/masked study

DVT Drop-out Economic evaluation Effect (as in effect measure, treatment effect, estimate of effect, effect size) Effectiveness Efficacy Elective Electrical stimulation Emergency

See Clinical effectiveness. See Clinical efficacy. Name for clinical procedures that are regarded as advantageous to the patient but not urgent. Designed to increase venous blood flow velocity out of the leg to reduce the incidence of post-surgical venous thrombosis. When admission is unpredictable and at short notice because of

26 admission Epidemiological study Equity Evidence

VENOUS THROMBOEMBOLISM PROPHYLAXIS clinical need. The study of a disease within a population, defining its incidence and prevalence and examining the roles of external influences (For example, infection, diet) and interventions. Fair distribution of resources or benefits. Information on which a decision or guidance is based. Evidence is obtained from a range of sources including randomised controlled trials, observational studies, expert opinion (of clinical professionals and/or patients). A table summarising the results of a collection of studies which, taken together, represent the evidence supporting a particular recommendation or series of recommendations in a guideline. Explicit standards used to decide which studies should be excluded from consideration as potential sources of evidence. Criteria that define who is not eligible to participate in a clinical study. See Consensus methods. If Option A is both more clinically effective than Option B and has a lower cost per unit of effect, when both are compared with a donothing alternative then Option A is said to have extended dominance over Option B. Option A is therefore more efficient and should be preferred, other things remaining equal. In data analysis, predicting the value of a parameter outside the range of observed values. Observation over a period of time of an individual, group or initially defined population whose appropriate characteristics have been assessed in order to observe changes in health status or healthrelated variables. The foot impulse device is designed to stimulate the leg veins (venous pump) artificially by compressing the venous plexus and mimicking normal walking and reducing stasis in immobilised patients. The extent to which the results of a study based on measurement in a particular patient population and/or a specific context hold true for another population and/or in a different context. In this instance, this is the degree to which the guideline recommendation is applicable across both geographical and contextual settings. For instance, guidelines that suggest substituting one form of labour for another should acknowledge that these costs might vary across the country. See Reference standard. How well a statistical model or distribution compares with the observed data. Stockings manufactured to provide compression around legs at gradually increasing pressures. There are two different standards for graduated compression stockings, the British Standard and the

Evidence table

Exclusion criteria (literature review) Exclusion criteria (clinical study) Expert consensus Extended dominance

Extrapolation Follow up

Foot impulse devices(FID) Generalisability

Gold standard Goodness-of-fit Graduated compression

GLOSSARY OF TERMS stockings (GCS) Grey literature Harms Health economics

27

European Standard. These are different to anti-embolism stockings which are used for the prevention of venous thromboembolism. Reports that are unpublished or have limited distribution, and are not included in the common bibliographic retrieval systems. Adverse effects of an intervention. The study of the allocation of scarce resources among alternative healthcare treatments. Health economists are concerned with both increasing the average level of health in the population and improving the distribution of health.

Health-related quality A combination of an individuals physical, mental and social wellof life (HRQL) being; not merely the absence of disease. Heparin-induced thrombocytopenia (HIT) Heterogeneity Low blood platelet count resulting from the administration of heparin (or heparin-like agents). Despite having a low platelet count, patients with this condition are at high risk of their blood clotting. Or lack of homogeneity. The term is used in meta-analyses and systematic reviews when the results or estimates of effects of treatment from separate studies seem to be very different in terms of the size of treatment effects or even to the extent that some indicate beneficial and others suggest adverse treatment effects. Such results may occur as a result of differences between studies in terms of the patient populations, outcome measures, definition of variables or duration of follow-up. See Heparin-induced thrombocytopenia. This means that the results of studies included in a systematic review or meta-analysis are similar and there is no evidence of heterogeneity. Results are usually regarded as homogeneous when differences between studies could reasonably be expected to occur by chance. A supposition made as a starting point for further investigation. Explicit criteria used to decide which studies should be considered as potential sources of evidence. The analysis of additional costs and additional clinical outcomes with different interventions. The mean cost per patient associated with an intervention minus the mean cost per patient associated with a comparator intervention The difference in the mean costs in the population of interest divided by the differences in the mean outcomes in the population of interest. The value (usually in monetary terms) of an intervention net of its cost compared with a comparator intervention. The INB can be calculated for a given cost-effectiveness (willingness to pay) threshold. If the threshold is 20,000 per QALY gained then the INB is calculated as: (20,000 x QALYs gained) Incremental cost.

HIT Homogeneity

Hypothesis Inclusion criteria (literature review) Incremental analysis Incremental cost Incremental cost effectiveness ratio (ICER) Incremental net benefit (INB)

28 Index

VENOUS THROMBOEMBOLISM PROPHYLAXIS In epidemiology and related sciences, this word usually means a rating scale, for example, a set of numbers derived from a series of observations of specified variables. Examples include the various health status indices, and scoring systems for severity or stage of cancer. The defined use of a technology as licensed by the Medicines and Healthcare products Regulatory Agency (MHRA). An analysis of the results of a clinical study in which the data are analysed for all study participants as if they had remained in the group to which they were randomised, regardless of whether or not they remained in the study until the end, crossed over to another treatment or received an alternative intervention. Outcomes that are related to the outcome of interest but may be more easily assessed within the context of a clinical study: for example, blood pressure reduction is related to the risk of a stroke. A method of prophylaxis that comprises the use of inflatable garments wrapped around the legs, inflated by a pneumatic pump. The pump provides intermittent cycles of compressed air which alternately inflates and deflates the chamber garments, enhancing venous return. The degree to which the results of a study are likely to approximate the truth for the participants recruited in a study (that is, are the results free of bias?). It refers to the integrity of the design and is a prerequisite for applicability (external validity) of a studys findings. See External validity. Healthcare action intended to benefit the patient, for example, drug treatment, surgical procedure, psychological therapy. The period of time during a surgical procedure. The total number of days a participant stays in hospital. See Product licence. A measure of health outcome which shows the number of years of remaining life expectancy. Average years of life gained per person as a result of the intervention. Physical (as opposed to chemical) agent used, in this context, to reduce likelihood of thrombosis. Mechanical methods of DVT prophylaxis work to combat venous stasis and include: anti-embolism stockings/ Graduated compression stockings (GCS), intermittent pneumatic compression devices (IPCD), foot impulse devices, also known as foot pumps (FID) All products, except medicines, used in healthcare for the diagnosis, prevention, monitoring or treatment of illness or handicap. The Executive Agency of the Department of Health protecting and promoting public health and patient safety by ensuring that

Indication (specific) Intention-to-treat analysis (ITT analysis)

Intermediate outcomes Intermittent pneumatic compression devices (IPCD) Internal validity

Intervention Intraoperative Length of stay (LOS) Licence Life year (LY) Life-years gained Mechanical

Medical devices Medicines and Healthcare Products

GLOSSARY OF TERMS Regulatory Agency (MHRA) Meta-analysis medicines, healthcare products and medical equipment meet appropriate standards of safety, quality, performance and effectiveness, and are used safely.

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A statistical technique for combining (pooling) the results of a number of studies that address the same question and report on the same outcomes t

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